With recent reductions in electronic equipment size, performance of electronic equipment has increased dramatically. Higher performance has resulted in more internal heat and higher operating temperature. Without effective dissipation of the internal heat, reliability and life span of the associated electronic equipment is adversely affected.
To dissipate heat from electronic equipment, conventional heat sinks and fans are used. Since heat is dissipated at a heat transfer rate proportional to a conventional heat sink's surface area, fins are attached to the heat sink to increase the surface area so more heat will be dissipated. However, small, modern electronic equipment size limits how many and how large fins can be, which provides an upper limit to how much heat can be effectively dissipated by a heat sink attached to the electronic equipment. Since heat pipes transfer heat at a much higher rate than heat sinks and fans and can be made to be much smaller than a heat sink and fan, heat pipes are excellent candidates for heat dissipation in small, high performance electronic equipment.
            ⅆ      Q              ⅆ      t        =      h    ·          A      ⁡              (                              T            0                    -                      T            env                          )            
Where                Q=Thermal energy in Joules        h=Heat transfer coefficient        A=Surface area of the heat being transferred        T0=Temperature of the object's surface        Tenv Temperature of the environment        
Specifically, the heat transfer coefficient (hwf) of a working fluid in a heat pipe is much higher than the heat transfer coefficient (ha) of air as in a heat sink or fan.
In a conventional assembly process of a heat pipe, tin is often used as a filler to braze components of the heat pipe together and is covered with flux to reduce oxidation of the tin. However, tin has a low melting point and heat-transfer coefficient (h) and is poorly suited to dissipate heat generated by high performance electronic equipment. In addition, traditional heat pipe components soldering with tin can not pass a reduction procedure at 400° C., is oxidized, produces sand holes, brazes the heat pipe assemblies to form heat pipes needs multiple steps and let gas into the heat pipe after thermal shock or using the heat pipe for a long time. Therefore, reliability of the heat pipe is poor.
The heat pipe is hollow and air-tight, has an internal cavity, an inside surface and a wick and has a vacuum inside to maintain its heat-transfer efficiency. However, flux covering the components of heat pipe may degrade performance of the wick on the inside surface inside the heat pipe and decrease the heat-transfer efficiency of the heat pipe by raising the evaporation and condensation temperatures of the working fluid.
In a conventional heat pipe manufacturing process, the heat pipe is usually between 100 millimeter and 300 millimeter in length, is cut to fit a product specification and sealed at one end. The sealed end cannot transfer heat. The bigger the heat pipe is, the longer the sealed end is. Therefore the sealed end reduces the heat-transfer efficiency of the heat pipe.